Eastwood cast the three real-life heroes in his film 15:17 to Paris.

At 87, Clint Eastwood is not only trying new things, he’s trying daring new things, and his new film 15:17 to Paris represents one of the most audacious gambits of his career. To dramatize the tale of three Americans who tackled and subdued a heavily armed Islamist terrorist on a train out of Amsterdam in 2015, Eastwood cast the young men, none of whom had professional acting experience, as themselves. It’s a decision with little precedent in the entire history of motion pictures.

The reason why few directors have ever taken this tack is acutely evident, though: The three childhood friends, Spencer Stone, Alek Skarlatos, and Anthony Sadler, don’t have much to offer in the way of facial expressions or vocal intonations. In short, they’re not actors, and Eastwood should have hired professionals.

A worse failing of the movie, though, is a flat, dull script by Dorothy Blyskal that frames the story in terms of the young men’s backgrounds. 15:17 to Paris is in essence a single gripping scene of about ten minutes puffed out to feature length. Though the movie is, at 94 minutes, the shortest of the 36 features Eastwood has directed, a large chunk of it is filler in which we watch the guys amble around tourist attractions in Rome, Venice, Berlin, and Amsterdam. Absolutely nothing of interest happens in any of these scenes — for instance, Stone and Skarlatos meet a girl in Venice, have pizza with her, and then she disappears and is forgotten — except Stone muses that he’s heading for something important in his life. That sense of purpose is tied in with his faith — all three of the principal characters are practicing Christians — and these days it is unusual for a mainstream Hollywood film to take an unabashed pro-Christian stance.

Some of the back story is relevant, especially the jiu-jitsu and first-aid-training courses Spencer takes in the Air Force, but much of it isn’t. As boys, Spencer and Alek are chided for their disciplinary problems and told they have attention-deficit disorder, which yields a scene in which their mothers (Judy Greer and Jenna Fischer) angrily yank them out of public school and place them in a Christian private school in Sacramento. But neither Skarlatos nor Sadler really emerges as a fleshed-out character, even though the former served in the Army in Afghanistan and was seemingly well-prepared for a moment such as the one on the train. Stone gets the most screen time and we do learn some critical things about him — during a false alarm about an active shooter supposedly roaming Fort Sam Houston, he alone waits by the door while everyone else is hiding under their desks because he hopes to confront the gunman with the only weapon he has on him, which is a ballpoint pen. Stone’s various difficulties in school and in the military (he had to lose some 30 pounds to get in shape when he enlisted) add some texture to his character, but not enough.

Some of the back story is relevant, especially the jiu-jitsu and first-aid-training courses Spencer takes in the Air Force, but much of it isn’t.

The film’s structural resemblance to American Sniper — starting out with a crucial action scene, then flashing back to the formation of character — creates an inevitable comparison that works very much to the disadvantage of 15:17 to Paris. Whereas Bradley Cooper’s haunted eyes told the story of Chris Kyle’s resilience and his weariness in the earlier film, Stone, not being an actor, is a blank slate unable to register any depth. Whereas American Sniper’s script built a foundation for the character’s honor with the story of the sheep, wolves, and sheepdogs, the youthful Stone is just an ordinary kid who enjoys playing paintball like any other. Where American Sniper had an immense gravitas, Stone makes his life-changing decision to join the Air Force because of a 30-second conversation over a Jamba Juice he serves to a passing Marine.

Stone, Skarlatos, and Sadler, who received the Légion d’Honneur from then-French president François Hollande after foiling the attack, deserve to be household names, especially Stone, who did the most to subdue the terrorist and nearly lost a thumb when the man lashed out with a knife. This film serves as a fitting monument to their heroics. But Eastwood and his screenwriter failed to build much of a movie around a few minutes of immense courage.